Hybrid electric vehicles use high-voltage batteries to power one or more electric machines and thereby deliver torque to the vehicle's driveline, either alone or in conjunction with an internal combustion engine. The term “plug-in vehicle” describes any vehicle, e.g., battery electric, hybrid electric, for instance by plugging a charging cable from the vehicle into a 120 VAC or 240 VAC wall socket. Regenerative braking may be used to recharge the battery when the vehicle is in operation.
An onboard charging module or OBCM may be used to facilitate recharging of the high-voltage battery. A typical OBCM has the required electronic circuit hardware and control software to convert single-phase or three-phase, alternating current (AC) grid voltage into a direct current (DC) voltage usable by the battery, and thus acts as a voltage rectifier. An OBCM not only increases the power factor of the rectified voltage but also boosts the rectified voltage magnitude, and thus acts as a boost converter. Additionally, the OBCM acts as a DC-DC converter to further regulate the DC voltage as needed when charging the battery.
An OBCM is described as being either an isolated design or a non-isolated design. In an isolated design of the type suitable for use in vehicles having an electric powertrain, galvanic isolation is maintained between the input and output sides of the OBCM. A transformer is a suitable galvanic isolator, as is well known in the art, as is any device that interconnects two electrical circuits without allowing electricity to flow directly from one electrical circuit to the other. In contrast, non-isolated OBCM designs lack galvanic isolation. As a result, non-isolated designs tend to be used most often in low voltage, non-vehicular designs.